In wireless communication systems, RRM is generally responsible for utilizing the air interface resources. RRM is used to guarantee quality of service (QoS), to provide efficient use of the radio resources, and to increase system capacity. RRM consists of admission control, handover, power control, and congestion control functionalities. Admission control can be divided into user admission control and call admission control. User admission control accepts or rejects the radio resource control (RRC) connection requested by a wireless transmit/receive unit (WTRU). Call admission control accepts or rejects a request to establish or modify a radio access bearer (RAB) in the radio access network (RAN). Call admission control is located in the controlling radio network controller (C-RNC).
There are two dynamic channel allocation (DCA) functions, slow DCA and fast DCA (S-DCA, F-DCA). The S-DCA allocates the radio resources to cells while the F-DCA allocates the radio resources to bearer service. Two F-DCA functions, which could be in the form of algorithms, are executed by RRM at steady state operation: one for background interference reduction procedure and one for an escape mechanism.
The F-DCA background interference reduction procedure is used to keep WTRU and system resource usage at a reasonable level at all times by reassigning radio resources (timeslots and codes) to an existing radio bearer. The F-DCA background interference reduction procedure is triggered by RRM periodically. The period to trigger the background interference reduction procedure is a design parameter; in a preferred embodiment of the present invention, the period is two seconds. It has relatively low priority among the three F-DCA algorithms.
Only one F-DCA function is preferably run at a given time in a C-RNC, because the output of one function may affect the decision of another function. If more than one of these functions are triggered at exactly the same time, the priority of these functions is such that the escape procedure runs first, call admission control runs second, and the background interference reduction procedure runs last.
It is desirable to provide an implementation of the background interference reduction procedure, which satisfies the foregoing requirements.